The use of implantable leads has been known for quite some time in medicine. Implantable leads are used in particular to connect electrical implants—generally cardiac pacemakers, defibrillators, cardioverters, and the like—to the site to be treated electromedically. In the field of application that has been known for a long time, this site is often the heart, on or in which the implantable leads are attached. Meanwhile, implantable leads which lead into the heart and are routed, for example, through the right atrium into the atrial appendage or into the apex of the right ventricle and are fixed there either by passive anchorings—known as “tines”—or by being screwed into the cardiac tissue, have become established. With certain indications, such implantable leads are also routed through the atrium of the heart into the coronary sinus (a coronary vessel, also referred to in short as “CS”), so as to conduct a therapy there on the left side of the heart.
All implantable leads mentioned and/or described in this patent application generally comprise an elongated electrode body, at the distal end of which, in addition to the aforementioned exemplary fixation options, at least one electrode pole is present, which delivers therapeutic signals and/or senses physiological signals. At the proximal end of the electrode body, located opposite of the distal end, at least one connector system is present, by which the implantable lead is connected to the electrical implant. Hereinafter, “distal” shall mean pointing in the direction of the explantation site and “proximal” shall mean pointing in the direction of the surgeon. Electrical connecting lines, by which the at least one electrode pole at the distal end is electrically connected to the connector system at the proximal end, run in the electrode body in the longitudinal direction. Moreover, the implantable lead can have a generally centrally extending continuous lumen, which at the proximal end, and optionally at the distal end, is connected to the surroundings. This lumen is used to guide the implantable lead along a previously placed guide wire, or by way of a mandrin. The electrode body can also comprise other elements, however, these will not be addressed here in detail.
Immediately after implanting an implantable lead, a natural process sets in which ensures adhesion of the implantable lead. To this end, generally tissue grows around the lead, at least on the electrode tip, which results in fixation. However, it is also possible for the implantable lead to experience adhesion not only at the tip, but in an undefined manner at the electrode body thereof, for example, in sites in which the implantable lead is in contact with the surrounding vascular or cardiac tissue. This adhesion process generally results in the implantable lead, which is made of material foreign to the body, not undergoing any rejection reaction.
From the view of a person skilled in the art or health professional, the disadvantage of this natural adhesion process is that the explantation of an implanted lead of the aforementioned type is very difficult, and at times even impossible. These explantations are quite often life-threatening for the patient.
Explantations are required, for example, when the implanted lead is defective, whereby no reliable stimulation or measured value recording is possible any longer. This can result in severe and life-threatening malfunctions of the electrical implant. Given the complexity and danger to life of an explantation, many physicians in the past decided to simply leave defective electrodes in the body without them having any function, instead of explanting them, and to run new functional implantable leads into the heart.
However, indications also exist in which a physician has no options and the implanted lead must be explanted in any case. Examples include infections of what is known as the pacemaker pocket—this is how the implantation site of the implant is referred to—or sepsis along the implanted lead. In these instances, the infection site must be removed as quickly as possible, resulting in inevitable explantation of the implanted lead.
A variety of aids are known in order to facilitate or enable the explantation of the implanted lead in these instances. Notably, cutting tools—also referred to as cutting sheaths—are known. These generally involve a hose-like or tubular body having a lumen and a proximal and a distal end, wherein the distal end comprises a detaching unit. For explanation purposes, this cutting sheath is guided over the implanted lead and pushed forward to the distal end of the lead. The detaching unit then has a detaching effect on the tissue adhering around the implanted lead. Detaching units are known from the prior art of cutters, which detach or “scrape” the tissue from the implanted lead by means of a blade pointing in the distal direction. A cutting sheath comprising such a detaching unit is technically simple, but it is not the most effective means for removing tissue from a grown-in implanted lead.
Detaching units operating based on high-frequency or laser technology are also known from the prior art. Such detaching units are technically so complex that the error rate in terms of use is very high. Another reason for this high error rate is that use is not easy and the physician loses any sensation as a result of this “active” cutting technique.
All of the aforementioned solutions, moreover, require the use of an opposing force, which is applied by anchoring what is known as a locking stylet at the distal end of the implanted lead. In order to apply the opposing force, the locking stylet is introduced into the central lumen of the implanted lead, advanced to the distal end of the implanted lead, and clamped there so that the implanted lead can no longer move with respect to the locking stylet. Thereafter, the stylet is fixed outside of the body and the cutting sheath comprising the detaching unit is displaced relative to the implanted lead with the locking stylet. The implanted lead is thereby fixed and acts counter to the cutting force directed in the direction of the distal end of the implanted lead. An example of such a locking stylet is described in U.S. Pat. No. 6,358,256.
Locking stylets have several disadvantages. For one, the use of such a stylet is always dependent on the presence of a central lumen. However, newer implantable leads, especially those for use in the CS or neural leads, frequently no longer have a central lumen. Secondly, it is advantageous to always position the application site for the opposing force in the vicinity of the detaching unit, which can be displaced relative to the implanted lead. With a locking stylet, however, releasing the clamping and repositioning with respect to the detaching unit on the cutting sheath are not possible. This often results in major problems when removing tissue in the more proximal region of the implanted lead because the implantable lead is very soft and flexible there, and the opposing force cannot always be directly transmitted. Moreover, it is important for the implanted lead not to undergo any change of the outer circumference so as to detach the implanted lead with only the necessary damage to the tissue.
A “locking sheath” according to the prior art is a refinement of the locking stylet and is likewise used to apply a force that opposes the cutting force. This locking sheath generally comprises a hose-like or tubular body having a lumen along a longitudinal axis and a distal and a proximal end. At the distal end, the locking sheath comprises a clamping device, the clamping direction of which acts radially in the direction of the longitudinal axis. For explantation purposes, the locking sheath is guided over the implanted lead and advanced to the adhesion. There, the clamping device is released, which is to say it acts in the direction of the implanted lead and clamps the implanted lead so that the implanted lead can no longer move with respect to the locking sheath. Thereafter, the locking sheath is fixed outside of the body and the cutting sheath comprising the detaching unit is displaced relative to the locking sheath with the implanted lead. The implanted lead is thereby fixed and acts counter to the cutting force directed in the direction of the distal end of the implanted lead. An example of such a locking sheath is described in U.S. Pat. No. 4,576,162.
The disadvantage of the solution described therein is that the distal end of the locking sheath located between the cutting sheath and the implanted lead has to be pushed out of the distal end of the cutting sheath to remove tension from the clamping device. This is unfavorable because no blade is present at the locking sheath. This means that the adhesion can be penetrated only to a limited extent, which requires multiple readjustments during the procedure. Moreover, the implanted lead is always fixed during the cutting operation, which may not be desirable in some circumstances.
According to a further embodiment of the prior art locking sheath, a detaching unit can also be arranged at the distal end. An example of this is provided in document U.S. Publication No. 2010/0198229. There, clamping is carried out at the proximal end by means of hydraulics. Hydraulic clamping, however, is complex to implement and difficult to handle manually.
It is therefore an object of the present patent application to provide a technically simple explantation device for implanted leads which is easy to use and offers improved fixation options, and a method for the use thereof.
The present application is directed toward overcoming one or more of the above-identified problems.